childish behaviour

When I was younger, in grade school, going through some bad times being bullied, etc. I remember thinking I can't wait until I grow up and become an adult because adults don't act childish.
HA! Talk about naive thinking!
Surely, I thought, by 3rd year University, gilrs, *ah'em, women, would not act like little children and stomp away in a huff only to return later, angry, and try to stir up trouble by lying or complaing to anyone who would listen. Clearly, I thought wrong!
There are some people in this world, I guess, who assume their ideas are the best, and won't consider or listen to any one else's thoughts or comments. And when they realize that a majority vote is in favour of someone else's superior idea, they leave... only to return a couple hours later crying that everyone else was ignoring them, and then getting angry because they were absent for the remainder of the decision making meeting and ended up with the "shit-job" that noone else wanted.
Well, honey, you snooze, you lose. "Grow up" is all I have to say to you. You are in 3rd year University, if you can't hack it and take criticism at this point in your life and academic career, well, then I suggest you crawl back under that rock where you have been living and leave the work to the responsible adults.